Valve device

1. A valve device for an exhaust system of an internal combustion engine, comprising: a valve flap arranged in a tube to assume a basic position and an actuating position; a motor-driven valve drive arranged outside the tube and which is coupled to a shaft of the valve flap by a force transmission element; a mechanical restoring element that urges the valve flap into the basic position, and wherein the motor-driven valve drive works against the mechanical restoring element as far as to the actuating position; and a lever arranged on a drive shaft of the motor-drive valve drive and connected to one end of the force transmission element, wherein in the actuating position of the valve flap, the lever is in or near a dead-center position with respect to a force transmission direction from or to the force transmission element.

2. The valve device according to claim 1 , wherein in the actuating position, the lever is situated in a range of ±15 degrees from the dead-center position.

3. The valve device according to claim 1 , wherein a control is provided for the motor-driven valve drive, the control switching the motor-driven valve drive off when the valve flap is in the basic position.

4. The valve device according to claim 1 , wherein the mechanical restoring element is arranged to move the valve flap to the basic position in case of failure of the motor-driven valve drive.

5. The valve device according to claim 1 , wherein at least outside the basic position, the motor-driven valve drive is in permanent operation and exerts a force on the lever.

6. The valve device according to claim 1 , including a stop against which the lever rests in the actuating position of the valve flap.

7. The valve device according to claim 1 , wherein the basic position the valve flap presses against a stop.

8. The valve device according to claim 1 , wherein the motor-driven valve drive acts only in one direction of rotation.

9. The valve device according to claim 1 , wherein the basic position comprises an open position and the actuating position comprises a closed position.

10. The valve device according to claim 1 , wherein the lever defines a pivot axis and wherein a force transmission direction extends through the pivot axis when in the actuating position.

11. The valve device according to claim 1 , wherein the lever defines a pivot axis, and wherein the force transmission direction is defined at a connection of the lever to the force transmission element, and wherein the force transmission direction extends along a line of action of the force such that the line of action intersects the pivot axis at only one of the actuating and basic positions.

12. The valve device according to claim 1 , wherein in the basic position of the valve flap, the lever is in a position in which a distance between the force transmission direction from or to the force transmission element and the pivot axis of the lever is at least approximately a maximum.

13. The valve device according to claim 1 , wherein the force transmission element is a wire of a Bowden cable.

14. The valve device according to claim 13 , wherein a sheath of the Bowden cable is pivotally mounted on an end facing the lever.

15. The valve device according to claim 1 , wherein the mechanical restoring element is a spring.

16. The valve device according to claim 15 , wherein the mechanical restoring element is a torsion spring.

17. The valve device according to claim 15 , wherein the mechanical restoring element is a helical spring.

18. A valve device for an exhaust system of an internal combustion engine, comprising: a valve flap arranged in a tube to assume a basic position and an actuating position; a motor-driven valve drive arranged outside the tube and which is coupled to a shaft of the valve flap by a force transmission element; a mechanical restoring element that urges the valve flap into the basic position, and wherein the motor-driven valve drive works against the mechanical restoring element as far as to the actuating position; and a lever connected to the force transmission element at one end and coupled to the shaft of the valve flap at another end, wherein in the actuating position of the valve flap, the lever is in a position in which a distance between a force transmission direction from or to the force transmission element and the pivot axis of the lever is at least approximately a maximum, and wherein in the basic position the lever is near a horizontal position without assuming the horizontal position.

19. The valve device according to claim 18 , wherein the basic position comprises a closed position and the actuating position comprises an open position, and wherein a force transmission direction extends through the pivot axis when in the closed position.

20. The valve device according to claim 18 , wherein when the valve flap moves to the closed position, the motor-driven valve drive is in a switched-on condition and generates a damping moment that counteracts the mechanical restoring element.

21. The valve device according to claim 18 , wherein the force transmission element is coupled to the lever by a length compensator comprising a spring.

22. The valve device according to claim 18 , wherein the lever defines a pivot axis, and wherein the force transmission direction is defined at a connection of the lever to the force transmission element, and wherein the force transmission direction extends along a line of action of the force such that the line of action intersects the pivot axis at only one of the actuating and basic positions.

23. A valve device for an exhaust system of an internal combustion engine, comprising: a valve flap arranged in a tube to assume a basic position and an actuating position; a motor-driven valve drive arranged outside the tube and which is coupled to a shaft of the valve flap by a force transmission element; a mechanical restoring element that urges the valve flap into the basic position, and wherein the motor-driven valve drive works against the mechanical restoring element as far as to the actuating position; and a lever connected to one end of the force transmission element, wherein in the actuating position of the valve flap, the lever is in or near a dead-center position with respect to a force transmission direction from or to the force transmission element, and wherein the force transmission element is coupled to the lever by a length compensator comprising a spring.

24. A valve device for an exhaust system of an internal combustion engine, comprising: a valve flap arranged in a tube to assume a basic position and an actuating position; a motor-driven valve drive arranged outside the tube and which is coupled to a shaft of the valve flap by a force transmission element; a mechanical restoring element that urges the valve flap into the basic position, and wherein the motor-driven valve drive works against the mechanical restoring element as far as to the actuating position; and a lever connected to one end of the force transmission element, wherein in the actuating position of the valve flap, the lever is in or near a dead-center position with respect to a force transmission direction from or to the force transmission element, and wherein the shaft of the valve flap is connected to a center of a roller, and an end of the force transmission element is fixed in place on a periphery of the roller.

25. A valve device for an exhaust system of an internal combustion engine, comprising: a valve flap arranged in a tube to assume a basic position and an actuating position; a motor-driven valve drive arranged outside the tube and which is coupled to a shaft of the valve flap by a force transmission element; a mechanical restoring element that urges the valve flap into the basic position, and wherein the motor-driven valve drive works against the mechanical restoring element as far as to the actuating position; and a lever connected to one end of the force transmission element, wherein in the actuating position of the valve flap, the lever is in or near a dead-center position with respect to a force transmission direction from or to the force transmission element wherein when the valve flap moves to the basic position, the motor-driven valve drive is in a switched-on condition and generates a damping moment that counteracts the mechanical restoring element.

26. A valve device for an exhaust system of an internal combustion engine, comprising: a valve flap arranged in a tube to assume a basic position and an actuating position; a motor-driven valve drive arranged outside the tube and which is coupled to a shaft of the valve flap by a force transmission element; a mechanical restoring element that urges the valve flap into the basic position, and wherein the motor-driven valve drive works against the mechanical restoring element as far as to the actuating position; and a lever connected to the force transmission element at one end and coupled to the shaft of the valve flap at another end, wherein in the actuating position of the valve flap, the lever is in a position in which a distance between a force transmission direction from or to the force transmission element and the pivot axis of the lever is at least approximately a maximum, and wherein when the valve flap moves to the basic position, the motor-driven valve drive is in a switched-on condition and generates a damping moment that counteracts the mechanical restoring element.

27. A valve device for an exhaust system of an internal combustion engine, comprising: a valve flap arranged in a tube to assume a basic position and an actuating position; a motor-driven valve drive arranged outside the tube and which is coupled to a shaft of the valve flap by a force transmission element; a mechanical restoring element that urges the valve flap into the basic position, and wherein the motor-driven valve drive works against the mechanical restoring element as far as to the actuating position; and a lever connected to the force transmission element at one end and coupled to the shaft of the valve flap at another end, wherein in the actuating position of the valve flap, the lever is in a position in which a distance between a force transmission direction from or to the force transmission element and the pivot axis of the lever is at least approximately a maximum, and wherein the shaft of the valve flap is connected to a center of a roller, and an end of the force transmission element is fixed in place on a periphery of the roller.

28. A valve device for an exhaust system of an internal combustion engine, comprising: a valve flap arranged in a tube to assume a basic position and an actuating position; a motor-driven valve drive arranged outside the tube and which is coupled to a shaft of the valve flap by a force transmission element; a mechanical restoring element that urges the valve flap into the basic position, and wherein the motor-driven valve drive works against the mechanical restoring element as far as to the actuating position; and a lever connected to the force transmission element at one end and coupled to the shaft of the valve flap at another end, wherein in the actuating position of the valve flap, the lever is in a position in which a distance between a force transmission direction from or to the force transmission element and the pivot axis of the lever is at least approximately a maximum, and wherein the force transmission element is coupled to the lever by a length compensator comprising a spring.